Butein is a cAMP-specific PDE inhibitor with an IC50 of 10.4 μM for PDE4[1]. Butein is a specific protein tyrosine kinase inhibitor with IC50s of 16 and 65 μM for EGFR and p60c-src in HepG2 cells[2]. Butein sensitizes HeLa cells to Cisplatin through AKT and ERK/p38 MAPK pathways by targeting FoxO3a[3]. Butein is a SIRT1 activator (STAC) .